This invention relates generally to public transportation seating and more particularly to an upper suspended cantilevered seat for a passenger carrying vehicle which is capable of absorbing impact energy imposed thereon by a passenger seated behind the seat during a crash or rapid maneuver.
In recent years efforts have been made to improve the crash worthiness of mass transportation vehicles such as school buses, city and interstate buses, trains and aircraft. Crash studies, particularly in the ground transportation industry, have shown that one of the major causes of injury to passengers in an accident is the result of being impacted or thrown into the vehicle seat structures. Many prior art seats fail to protect the passengers by being too weak, too low, or too hostile. In a conventional mass transportation vehicle such as a bus, passengers are thrown from their seats forwardly into the next adjacent seat. If the back seat of the next adjacent seat is too low, they could be catapulted over the top of the seat and impact the interior of the vehicle, with severe injury. Further, if the seat structure against which the impact occurs is too weak or is incapable of absorbing sufficient energy in a controlled manner, the seat structure may fail, similarly permitting the passenger to be thrown forward, resulting in severe injury. Efforts have been made to reduce the hostility of the seats by removing or redesigning grab rails or like structures of the seats which during a crash situation, could become blunt or sharp instruments capable of inflicting severe, and sometimes fatal injury to the passengers.
In the mass transportation industry, and in particular in buses, active restraint systems such as seat belts have not received ready acceptance, due primarily to the nature of the vehicles involved and their uses. Because of the large number of passengers using these vehicles, it is extremely difficult for a single operator to enforce the use of seat belts. Therefore, the trend, particularly in buses, has been to provide for crash worthiness with passive restraint systems.
In order to increase the safety of vehicles and in particular buses, efforts have been directed to arranging the interiors so that the passengers are compartmentalized. Each compartment includes an interior sidewall of the vehicle, the passengers own seat, and the seat immediately in front of the passenger. The design emphasis on the seats themselves is to provide a seat which is capable of absorbing impact energy in a controlled manner within certain levels so as to reduce or prevent the occurrence of, and severity of injuries to the passengers.
In an effort to provide crash protection, and in accordance with the mandate set forth in the National Motor Vehicle Safety Act of 1966, 15 USC, 1381, et seq., as amended by Public Law 93-492 in 1974, the Department of Transportation, Urban Mass Transportation Administration has issued a Base Line Advanced Design Transit Coach Specification which sets forth certain criteria relating to energy absorbtion and compartmentalization characteristics which must be met by public mass transportation vehicle seating. A separate criterian is set out for school bus passenger seating.
Attempts have been made to fabricate seats in accordance with the aforementioned criteria. Typically, these seats have employed large amounts of padding or energy absorbing material to meet the required standards. The resulting seats have been aesthetically unpleasing and possess the disadvantages of relatively high weight when compared to previously employed seats and relatively complex construction and bulkiness. These seats also suffer from relatively high cost of manufacture and installation.
The most successful prior art seats designed to meet these criterian have involved the use of a freestanding upright back structure which is deflectable upon impact for absorbing the impact energy of a passenger. Such a design may include a seat bench cantilevered from a sidewall of the vehicle or mounted on pedestals from the floor of the vehicle. In the prior art, pedestal designs have also been provided including additional energy absorbing means contained in the bench for allowing a certain amount of linear translation of the seat bench. Of these prior art designs, the cantilevered seating structures have become most desirable from several viewpoints. This type of seat eliminates the usual obstructions connecting the seat to the floor, such as legs, pedestals, aisle end bases or the like. An inportant advantage of such a cantilevered type seat is that a gang-type sweeper may be used to clean the entire width of the vehicle in a single sweep, thereby substantially reducing the time and cost of cleaning. There are however other advantages to cantilevered seats, including a more pleasant and neater appearance, greater facility of ingress and egress, elimination of stumbling hazards that legs or bases may contribute to passengers walking down a narrow aisle or exiting from the seat, and ease of retrieving articles from beneath the seats. The latter advantage stemming from the fact that an unobstructed view of the floor area is provided and the available light shines upon this unobstructed area. Furthermore, depending on the seat structure, there may be more room for storage of luggage beneath the cantilevered seat as well as increased area for the legs of the passengers located behind the seat.
Prior art cantilevered seating arrangements that have met the aforementioned energy absorbtion and compartmentalization criterian have been platform mounted lower support cantilevered seats. These prior art cantilevered seats employed a lower platform structure having a three point mounting arrangement for securing the bench portion of the seat to a sidewall of the vehicle. The platform was attached to the sidewall of the vehicle by two horizontally spaced attachment points with a third attachment point displaced vertically below the bench portion of the seat to triangularly brace the cantilevered seat bench. Prior art upper suspension type cantilevered seat structures with at least one mounting point disposed high on the seat back, in place of the triangulated platform structure, have been unable to meet appropriate safety standards on the window side of the seat.